In 1859, the Carrington storm caused spectacular auroras and electrical disturbances in telegraph networks as far south as Cuba. 167 years later, a repeat could cripple key infrastructure while leaving some electronic devices surprisingly unaffected

On September 1, 1859, astronomer Richard Carrington watched an extraordinary flash erupt across a group of sunspots. Less than a day later, Earth was hit by one of the most powerful geomagnetic storms ever recorded. Auroras appeared far beyond their usual range, reaching places as far south as Cuba and Hawaii. Telegraph equipment malfunctioned, sparks flew and operators reported electric shocks.

A similar storm today would meet a world filled with power grids, satellites, navigation systems and communications networks. But it would not simply switch off every electronic device on Earth.